This invention relates to a microcomputer formed on a single semiconductor chip, and more particularly to microcomputer technology which is effective when utilized for the servo systems of video tape recorders etc.
Video tape recorders (hereinbelow, termed "VTRs") for domestic use, which are presently available as manufactured articles, are classified into VTRs of the type which is combined with a camera and VTRs of the type which is fixedly installed. As systems for recording audio signals and video signals on magnetic tapes, there are various systems such as the VHS system, SVHS system, VHS-C system, SVHS-C system, beta system and ED beta system.
Each of the VTRs includes a drum motor for rotating a drum on which a plurality of magnetic heads serving to derive the audio signals and video signals from the magnetic tape are mounted, a capstan motor for feeding the magnetic tape, and a servomechanism for automatically controlling the rotational speeds of the drum and capstan motors, etc. Such servomechanisms are brought into multifarious forms due to differences in the aforementioned recording systems, differences in the number of the magnetic heads, etc.
Meanwhile, VTR servo technology is about to progress from analog servo technology software servo technology through the use of digital microcomputers. The software servo technology is intended to automatically control, for example, the rotational speeds of the drum and capstan motors in software fashion by the use of a microcomputer. Examples of the software servo microcomputer which has a built-in hardware unit (group of timers) for VTRs (especially for 8 mm-VTRs), are `CXP80116` offered by Sony Corporation and `.mu.PD78112` offered by Nippon Electric Co., Ltd.
Since both the software servo microcomputers adopt constructions directed toward the VTRs of specified systems, they have the disadvantage of limited applications. Even in the VTRs of the VHS system by way of example, when the numbers of the heads or methods of generating specific waveforms or timing signals are different, the hardware needs to be reassembled in accordance with the respective sorts.